Harden block-recording pipeline: P0 reliability fixes

Closes the silent-failure modes between "ckpool logs a solve" and
"block correctly displayed":

* Difficulty estimate matched mempool.space — the projection now uses
  (inEpoch + 1) intervals so it converges on Bitcoin Core's eventual
  retarget formula at end-of-epoch instead of undershooting by ~0.05–
  0.10 % throughout.

* Tailer resumes mid-log on restart — persists (inode, offset) to kv
  every EOF + on shutdown, and replays the unread tail next time. Any
  solve line written while kamado-api was down would previously be
  invisible forever.

* Background reconcile loop (60 s) retries hash/reward enrichment for
  blocks the original RPC missed, so a transient bitcoind-index race no
  longer permanently leaves a block hashless.

* Reorg detection: same loop compares each recent stored hash against
  getblockhash(height); a mismatch stamps orphaned_at. UI renders these
  strikethrough with a red "orphaned" tag instead of showing illusory
  rewards forever.

* InsertBlock now reports whether a row was actually inserted; the
  caller WARN-logs duplicate-height ignores so a re-mined orphaned
  height can't disappear silently.

* Submit-attempt vs confirmed counters surface failed submissions:
  every "Possible/Submitting block solve" log line increments
  block_submit_attempts; "Solved and confirmed" increments
  block_submits_confirmed. A growing gap means bitcoind is rejecting
  our submissions — previously invisible.

* share_err patch refreshed against pinned ckpool source: added
  SE_NO_JOBID -> 21 and SE_WORKER_MISMATCH -> 24 mappings, kept
  SE_INVALID_NONCE2 in 20 (it's a malformed-input error, not low-diff).
  AxeOS users now see actionable Stratum codes instead of
  "unknown error".

UI gets new orphaned_at + block_submit_attempts/confirmed fields on
the snapshot type and a strikethrough-with-tag rendering for orphaned
blocks in BlocksTable.

ui/src/types.ts

@@ -94,6 +94,10 @@ export type BlockRecord = {
   found_at: string; // RFC 3339
   source: string;
   share_diff?: number;
+  // Set when the periodic chain reconciler finds the recorded hash no
+  // longer matches the canonical block at this height (network reorged
+  // us out). UI renders these strikethrough.
+  orphaned_at?: string; // RFC 3339, omitted when zero
 };
 
 export type HashratePoint = {
@@ -123,6 +127,11 @@ export type Snapshot = {
   // Optional override for explorer links. Empty/undefined means the
   // UI falls back to its mempool.space defaults.
   mempool_base_url?: string;
+  // Submission attempt tracking — count of "Possible block solve"
+  // log lines vs "Solved and confirmed" lines. A growing gap means
+  // submissions are being rejected by bitcoind.
+  block_submit_attempts: number;
+  block_submits_confirmed: number;
   ckpool_ok: boolean;
   bitcoin_ok: boolean;
   last_error?: string;